Aspect ratio on three-dimensional stability analysis of slurry-supported trenches in non-uniform and anisotropic clay

Current analytical methods for evaluating the stability of slurry-supported trenches usually fail to incorporate trench width, potentially leading to overestimated safety margins, particularly in short trenches. To address this limitation, a novel three-dimensional (3D), multi-block mechanism based on translational movements, derived using the kinematic approach of limit analysis is developed. The proposed method allows failure to extend beyond the trench length, incorporating corner effects on trench stability evaluation. The resulting upper-bound stability numbers for trenches in uniform, isotropic clay outperform existing analytical solutions when the trench length-to-depth ratio is less than 0.3. This study reveals two distinct trench failure modes: composite failure, where collapse mobilizes soil on both trench faces in very short trenches, and back failure, where soil movement is confined to the trench face in longer trenches. Additionally, parametric study is carried out to investigate the influence of aspect ratio on trench stability in non-uniform and anisotropic clay, providing further insights into trench stability across various trench geometries.